Which of the following is a typical feature of employee stock option plans in the U.S.?

A. Employees are allowed to sell their options after the vesting period.

B. Employees who leave their jobs voluntarily during the vesting period must exercise their options.

C. Employees who are fired from their jobs after the vesting period must exercise in-the-money options.

D. When an employee exercises options, the company issues new shares and sells them to the employee at the current market price.

E. None of the above